Interpretive Summary: The objective of the current study was to determine if metal perches during all or part of the life cycle of White Leghorns affected hen musculoskeletal health, especially at end of lay. There were four treatments: treatment 1, birds represented control which never had access to perches during their life cycle; treatment 2, birds had perches only during the egg laying phase of the life cycle (17 to 71 wk of age); treatment 3, birds had perches during the growing or pullet phase (0 to 16.9 wk of age); and treatment 4, birds always had access to perches (0 to 71wk of age). Results showed that muscle deposition of 71-wk-old hens was increased by providing perches during the pullet phase. In addition, hens' bone mineralization was increased by accessing perches during the laying phase. However, the increase in bone mineralization of the keel bone as a result of perch access was not great enough to prevent a higher incidence of keel bone fractures at the end of lay. Perch re-design could be a solution to minimize keel fractures and deviations for improving caged hen well-being. These data can be used by egg producers to develop guidelines for improving chicken welfare by providing perches.

Technical Abstract:
A major skeletal problem of conventionally caged hens is increased susceptibility to osteoporosis mainly due to lack of exercise. Osteoporosis is characterized by a progressive decrease in mineralized structural bone. Whereas considerable attention has been given to enriching laying cages, little research has been conducted on providing caged pullets with furnishments, in particular perches. The objective of the current study was to determine if metal perches during all or part of the life cycle of White Leghorns affected hen musculoskeletal health, especially at the end of lay. Treatments during the pullet phase (hatch to 16.9 wk) entailed cages with and without perches. Four treatments were used during the laying phase (17 to 71 wk of age). Treatment 1 chickens never had access to perches at any point during their life cycle, typical of egg industry practices in the United States for conventional cages. Treatment 2 chickens had access to perches only during the egg laying phase which was from 17 to 71 wk of age. Treatment 3 chickens had access to perches only during the pullet phase (0 to 16.9 wk of age). Treatment 4 chickens had perch access throughout their entire life cycle (0 to 71wk of age). Musculoskeletal health was assessed by measuring bone mineralization, muscle weights, bone fracture incidence, and keel bone deviations. Though muscle deposition of 71-wk-old hens increased if given access to pullet perches and the bone mineralization of 71- wk-old hens also increased if given perch access as adults, it was not without the adult perch causing a higher incidence of keel deviations and fractures at end of lay. The increase in bone mineralization of the keel bone as a result of perch access during the pullet and laying phases was not great enough to prevent a higher incidence of keel bone fractures at the end of lay. Perch re-design and placement of perches within the cage to minimize keel fractures and deviations are possible solutions.